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Investigation of toxic pollutants formation with renewable fuels in a diesel engine using in-cylinder sampling

Ogbunuzor, Christopher Chinedu; (2020) Investigation of toxic pollutants formation with renewable fuels in a diesel engine using in-cylinder sampling. Doctoral thesis (Ph.D), UCL (University College London).

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Abstract

Intensifying awareness regarding the negative impact on public health of combustion-derived pollutants has led to increasingly stringent legislation limiting gaseous emissions, and levels of both particulate mass and number from road transport. Polycyclic aromatic hydrocarbons (PAH) are potentially carcinogenic pollutants emitted by diesel engines, both in the gas-phase and adsorbed onto particulate matter (PM) surface. While displacement of fossil fuels by renewable oxygen-bearing fuels has been observed to impact on the mass of PM emitted, there is limited understanding as to how fuel blend composition impacts PM mass concentration levels, PAH formation, and PM toxicity during combustion. To investigate fuel blends composition effects, PM and gaseous emissions present in the combustion cylinder gas and exhaust gas extracted during engine tests were collected. All compounds adsorbed on the samples were recovered, with the 16 US-EPA priority PAH species were identified and quantified. Despite not containing any fuel PAH, results showed that partially displacing diesel with 20% wt/wt oxygenate fuels (biodiesel or methyl decanoate) increased PM and the total PAH (gaseous and PM-bound) levels in the combustion cylinder. Furthermore, the presence of methyl decanoate, in the test fuel also increased toxic 5- and 6-ring PAH species during combustion to levels which exceeded that present during 100% diesel combustion, in contrast to the effect of biodiesel, likely due to a shorter alkyl chain, single-component nature and more saturation relative to biodiesel. However, in the exhaust, both oxygenate fuel blends emitted lower PM and PAH levels relative to 100% diesel, but favoured the persistence of benzo[a]pyrene, a highly toxic typically PM-bound PAH. Furthermore, diesel displacement with higher proportions of the oxygenate fuels influenced PAH formation and composition by favouring the persistence of dibenz[ah]anthracene, another highly toxic PAH species, in exhaust PM. Consequently, diesel displacement with oxygen-bearing fuels increased PM toxicity, with that of pure biodiesel being the most toxic, and was confirmed by in-vitro toxicological analysis.

Type: Thesis (Doctoral)
Qualification: Ph.D
Title: Investigation of toxic pollutants formation with renewable fuels in a diesel engine using in-cylinder sampling
Event: UCL (University College London)
Language: English
UCL classification: UCL
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Chemical Engineering
URI: https://discovery.ucl.ac.uk/id/eprint/10117886
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